Plug connector with switch for auxiliary starting circuit



1962 R. H. MOTTEN, JR 3,057,975

PLUG CONNECTOR WITH SWITCH FOR AUXILIARY STARTING CIRCUIT Filed May 2, 1960 5 3 801, 2 [7 5 M I I,

United States Patent 3,057,975 PLUG CONNECTOR WITH SWITCH FOR AUXILIARY STARTING ClRCUlT Roger H. Motten, Jn, Erie, Pa., assignor to Marathon Electric Manufacturing Corporation, Wausau, Wis., a

corporation of Wisconsin Filed May 2, 1960, Ser. No. 26,211 1 Claim. (Cl. 200-511) This invention relates to electrical plug-in connectors, and has as its general object to provide an electrical plug having prongs adapted to be received in an outlet receptacle, and having means whereby an auxiliary circuit may be momentarily energized concurrently with insertion of the plug into a receptacle. A plug connector of this type is shown in the copending application of Edward B. Sleeter, Serial No. 805,185, now Patent No. 2,957,955, filed April 9, 1959.

Certain types of electrical devices have auxiliary circuits that must be energized for a short time when the device is started, concurrently with initial energization of the main circuit. A fluorescent light, for example, has a starting circuit that must be energized briefly when the light is turned on, and which is then turned off after the lamp has been fired up by an initial surge of relatively high voltage, whereupon the lamp continues to operate on its normal rated line voltage.

Some types of electric motors commonly used in such appliances as non-automatic washing machines, home workshop tools, ironers, fans and the like also have auxiliary circuits which are closed for only a few seconds during starting, to energize starting windings, and which are then opened after the motor has come up substantially to its rated speed. In most cases the auxiliary starting circuits of such motors were heretofore controlled by automatic switches actuated by centrifugally responsive instrumentalities or other means responsive to the speed of the motor.

Whether provided with manual or automatic means for controlling the starting circuit, the running energization of devices incorporating auxiliary circuits could often be satisfactorily controlled without the use of a switch because the standard plug-in connectors by which such devices were connected to electrical outlets satisfactorily provided for making and breaking their connections to a current source. But the elimination of a main switch, and the saving resulting therefrom, was only a half-way measure, since there still remained the necessity for providing either automatic or manually operable switch means for controlling the auxiliary starting circuit.

The aforesaid copending application of Edward B. Sleeter discloses and claims a male plug-in connector which is adapted to be received in a standard electrical outlet receptacle and which incorporates a switch for controlling an auxiliary circuit that is adapted to be closed in consequence of insertion of the plug into a receptacle and to be opened when the plug is released. While generally satisfactory for its intended purpose, the plug of that application is somewhat complicated and expensive to manufacture and therefore does not fully realize the convenience and economy that can be effected with a device of the type here under consideration.

With the foregoing in mind, it is an object of this invention to provide a very simple, compact and inexpensive electrical plug-in connector of the type that incorporates a switch for controlling an auxiliary starting circuit, and which provides for substantially automatic momentary energization of the auxiliary circuit concurrently with insertion of the plug into an outlet receptacle, to thus eliminate the need for either automatic or manually operated switch means in devices having auxiliary starting 3,057,975 Patented Oct. 9, 1962 circuits, thereby substantially reducing the overall cost of such devices.

More specifically, it is another object of this invention to provide a special power cord plug for an electrical device having an auxiliary circuit, which plug incorporates means for closing the auxiliary circuit as a consequence of squeezing the body of the plug during its insertion into an outlet receptacle and for opening said circuit when the plug body is released, to thus eliminate the need for a separate automatic or manually operated switch such as heretofore been generally used to control the auxiliary circuits of such devices.

It is also an object of this invention to provide a plug-in connector for an electrical device having main and auxiliary circuits, which connector incorporates a normally open switch for controlling the auxiliary circuitand has a housing body that is molded or otherwise formed from resiliently flexible material, with an integral wall portion that is flexible inwardly and outwardly and which carries the movable contactor for said normally open switch, so that the switch may be closed simultaneously with insertion of the connector into a standard plug or outlet receptacle by squeezing the housing body to flex said Wall portion inwardly, and so that mere release of the housing body after a period of time opens the switch to break the auxiliary circuit.

Another object of this invention is to provide a male electrical plug of the type adapted for attachment to the power cord of an electrical appliance, and intended to be received in a standard outlet receptacle, which plug has prongs embedded in a resiliently flexible housing body and projecting forwardly therefrom, and has a movable contactor that is embedded in a wall portion of the housing body which is flexible inwardly and outwardly so that the movable contactor may be engaged with a fixed contact on one of the prongs by merely squeezing the housing body to flex said wall portion inwardly.

Thus it is a further object of this invention to provide an electrical plug-in connector of the character described having a built in normally open switch for an auxiliary power circuit, wherein the electrically conductive elements of the device are all partially embedded in a resiliently flexible housing body which can be molded in a single very simple operation and which securely holds the electrically conductive elements in their proper relationship and insulates them from one another.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claim, it 'being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claim.

The accompanying drawing illustrates one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical applicationof the principles thereof, and in which:

FIGURE 1 is a longitudinal sectional view through the electrical plug-in connector of this invention with the switch for the auxiliary circuit in open position;

FIGURE 2 is a view similar to FIGURE 1 but showing the switch for the auxiliary circuit in its closed position;

FIGURE 3 is a front view of the plug-in connector; and

FIGURE 4 is a side elevational view of the connector.

Referring now more particularly to the accompanying drawing, the numeral 5 designates generally a male electrical connector plug of this invention having a housing body 6 from which a pair of elongated conductive prongs 7 and 8 project forwardly in spaced apart parallel relationship to be received in a standard female outlet receptacle (not shown). Connected to the rear portions 10 of the prongs, as by spot Welding or soldering, are conductors 11 and 12 which extend rearwardly out of the housing body for connection with the main energizing circuit of an electrical appliance (not shown). The connector plug of this invention also includes a movable switch contactor 13 in the housing body to which is connected a conductor 14 of an auxiliary circuit and which cooperates with a fixed contactor 15 on the rear portion of one of the prongs 8.

More specifically, the housing body 6 of the plug is molded or otherwise formed from a resiliently flexible insulating material such as rubber, neoprene or vinyl. It has a generally rectangular cross section, and at one narrow side thereof it has an integral flexible wall member 17 connected with the main portion 18 of the body by short integral Wall segments 19, all defined by a forwardly opening well or cavity 20. The rear portions 10 of the prongs, and portions of the conductors 11 and 12 connected to them, are embedded in the main portion 18 of the body, while the movable switch contactor 13 is partially embedded in the flexible wall member 17. Those skilled in the art will recognize that the Well or cavity 20 may be readily formed by a core in the die (not shown) in which the plug is molded, and that the prongs 7 and 8, the movable contactor 13 and the end portions of conductors 11, 12 and 14 are all molded into the housing body when it is formed.

To insure adequate sturdiness of the unit, about half of the length of the prongs is embedded in the main portion 18 of the housing body, and the length of each conductor that is embedded in the body material preferably is about equal to the length of the embedded rear portions 10 of the prongs. The prongs and the movable contactor 13 may be straight along their entire lengths or may be bent, as at 16, to laterally offset their rear end portions so that they will better resist endwise displacement. In either event the embedding of the prongs and conductors in the housing body material insures that the prongs and the movable contactor will be held in the proper laterally spaced apart relationship to one another, that the conductors will be held by the material of the housing body against endwise separation from the conductive elements to which they are attached, and that the prongs will be adequately insulated from one another and from the movable contactor.

Preferably the movable contactor 13 comprises a short conductive strip extending parallel to the prong 8, and partially embedded in the flexible wall member 17 of the plug body, to be movable toward and from the prong 8 as said wall member is flexed in and out. The movable contactor terminates short of the front of the housing body, and its rear end portion, to which the conductor 14 is fastened, extends into the housing body a short distance behind the rear end of the cavity or Well 20, so that the material of the body provides reinforcement for the connection between the contactor and the conductor 14- and movably supports the contactor. A contact point 21, riveted or otherwise secured to the front end portion of the movable contactor, projects laterally into the cavity 20, toward the prong 8, and cooperates with the fixed contactor 15 similarly secured to the prong 8.

The two contacts 21 and 15 are normally spaced apart, but they are adapted to be brought into circuit making contact with one another when the housing body is squeezed to flex the wall member 17 inwardly, as during insertion of the plug into a receptacle. Such engagement of the contact points of course completes an auxiliary circuit through the conductors 12 and 14, but when the plug is released the movable contactor 13 springs away from the fixed contactor 15 as the wall member 17 flexes outwardly, opening the auxiliary circuit.

To facilitate inward flexing of the resilient wall member 17, the short wall segments 19 that connect it to the main portion 18 of the plug body may be disposed at oblique angles to one another and to the wall member 17, so that the wider side surfaces of the housing body will have shallow V-shaped grooves 22 that extend forwardly to the front end of the body.

To enable the movable contactor 13 to be securely held in the die in which the plug body is molded, the die will have to be so formed as to leave a space between the front end portion of the movable contactor and the front end portions of the adjacent wall members 17 and 19. This space can be filled, after the housing body is molded, by a small channel shaped plug or filler 23 of insulating material that embraces the front end portion of the movable wall member and thus helps to transmit to it the inward flexing movements of the wall member 17. Preferably a portion 24 of this filler overlies the front tip of the movable contactor.

From the foregoing description taken together with the accompanying drawing it will be readily apparent that this invention provides an inexpensive, simple, safe and compact electrical plug-in connector which is cooperable with a conventional outlet receptacle and which incorporates a normally open switch for controlling an auxiliary starting circuit that is adapted to be closed by squeezing the plug body in a normal and natural manner as the plug is inserted into a receptacle and to open upon release of the plug body. It will also be apparent that the connector of this invention comprises a very few simple and inexpensive parts which are assembled by the operation of molding the resilient plug body and which are held in proper relationship and safely insulated from one another by the plug body material.

What is claimed as my invention is:

A combined male electrical connector plug and momentary contact switch of the character described, comprising: a one-piece molded body of resilient material which is elongated fore and aft and which has a forwardly opening cavity near one side thereof defining an integral flexible wall portion spaced from the main portion of the body and connected therewith by opposite side walls, said side walls being considerably thinner than said flexible wall portion so as to be easily collapsed by inward pressure upon said wall portion; a pair of elongated metal prong strips having rear portions embedded in the body at the side of the cavity therein remote from said flexible wall portion, and having front portions projecting forwardly from the body to provide prongs engageable in an electrical outlet receptacle, one of said prong strips having an electrical contact thereon which is exposed in said cavity and is spaced from but faces the flexible wall portion; and an elongated metal contact strip embedded in the body and extending substantially fore and aft therein, said contactor strip having its front portion fiatwise adjacent to the inner face of said flexible wall portion so as to be movable laterally in a direction toward the contactor on said one prong strip in consequence of inward flexure of said wall portion, and having an electrical contact on its front portion exposed in said cavity opposite and normally spaced from the electrical contact on said one prong strip but engageable therewith upon inward flexure of the flexible wall portion, the open front end of the cavity affording access to the contacts for inspection and cleaning when needed.

References Cited in the file of this patent UNITED STATES PATENTS 

